1. Field of the Invention
This invention relates to use of low molecular weight polymers (oligomers) as insolubilizers for binders in paper coating compositions.
2. Description of the Prior Art
Polymers have been used as insolubilizers for binders in paper coating compositions.
U.S. Pat. No. 3,869,296--Kelly, Jr. et al., issued Mar. 4, 1975, describes paper coating compositions containing a pigment, starch as binder for the pigment and a insolubilizing agent for the binder, being the reaction product of glyoxal and urea at a mole ratio of 1.0 mole glyoxal to from about 0.5 mole to about 0.75 mole of urea. These compositions cure at low temperatures, are stable and provide coatings which possess high wet-rub resistance.
U.S. Pat. No. 3,917,659--Glancy et al., issued Nov. 4, 1975, describes dry, solid glyoxal-urea products obtained by drying the reaction product of 1.0 mole glyoxal to from 0.25 mole to 0.9 mole of urea. These products are useful in paper coating compositions.
U.S. Pat. No. 4,343,655--Dodd et al., issued Aug. 10, 1982, describes paper coating compositions containing at least one pigment, at least one binder and as an insolubilizer for the binder an alkylated product of the reaction of glyoxal and a cyclic urea at a mole ratio of about 0.5 to about 2.0 mole glyoxal to 1.0 mole of cyclic urea.